Floor cleaning in public, commercial, institutional and industrial buildings have led to the development of various specialized floor cleaning machines, such as hard and soft floor cleaning machines. These cleaning machines generally utilize a cleaning head that includes one or more cleaning tools configured to perform the desired cleaning operation on the floor surface. These cleaning machines include dedicated floor sweeping machines, dedicated floor scrubbing machines and combination floor sweeping and scrubbing machines.
An example of a dedicated hard floor sweeping and scrubbing machine is described in U.S. Pat. No. 5,901,407, which is assigned to Tennant Company of Minneapolis, Minn. and which is hereby incorporated by reference in its entirety. The machine uses a cleaning head having two cleaning tools in the form of cylindrical brushes. The cleaning tools counter-rotate in the directions indicated by the arrows shown. Water and detergent are sprayed on the floor ahead of the brushes so the brushes can scour the floor at the same time they are sweeping debris from the floor. A vacuum squeegee removes liquid waste from the floor during the wet scrubbing and sweeping operations. The cleaning tools engage each other such that debris on the floor is swept between the two cleaning tools and is directed into a waste hopper by a deflector.
An example of a dedicated floor sweeper is described in U.S. Pat. No. 4,571,771, which is assigned to Tennant Company of Minneapolis, Minn. and is hereby incorporated by reference in its entirety. The floor sweeper includes a cleaning head comprised of a rotating cylindrical brush that contacts the floor and throws loose debris into a hopper which is periodically emptied either manually or through a motorized lift. Combination floor sweeping and scrubbing machines were developed to avoid the necessity of having two machines. Some floor sweeping and scrubbing machines were created by mounting sweeping components to the front end of a dedicated scrubbing machine to making one large, multi-function machine.
When a surface maintenance machine performs wet scrubbing operation, water and detergent from a solution tank are sprayed or poured on the floor through a solution valve to the brushes. As the surface maintenance machine moves forward, a squeegee wipes the waste water off the floor, and a vacuum system applies suction to remove the waste water from the floor upwards through a recovery hose and into a recovery tank. When the vacuum supply is turned off, any waste water still present in the recovery hose flows down to the floor due to lack of suction. This is referred to as hose runoff Hose runoff is typically prevented by tying a knot or including a loop in the recovery hose.
Some prior art means for preventing hose runoff include a narrow water trap built on top of a vacuum squeegee. The waste water collects inside the water trap and is emptied with the assistance of jets of air created by the vacuum system. The shape of the water trap introduces swirling vortices from the air jets created by the vacuum system. These swirling vortices are deployed to remove water and debris from the water trap prior to shutting off the vacuum to prevent over flow of the water trap. The prior art water traps comprise fasteners and mounting means for the water trap on the squeegee, increasing the packaging and footprint. Additionally, the water traps mounted on the squeegee are limited by the dimensions of the squeegee, resulting in shapes that do not introduce swirling vortices of sufficient velocity to effectively remove waste water and debris from water trap. Such low velocity swirling vortices are also accompanied by large pressure losses. Designs that introduce large pressure losses in the recovery system require a larger capacity vacuum fan for drawing the same quantity of waste water in comparison to designs with lower pressure losses. Large pressure losses also translate to a higher input power to the larger capacity vacuum fan and loss of overall efficiency of the recovery system. In addition, the shape of the water trap may also allow non-uniform velocity of fluids at the inlet of the water trap resulting in “dead zones” that permit accumulation of debris.